This invention relates to dentistry in general and more particularly to a dental tool which permits a variable longitudinal extension of the shank of the tool from a tool holder associated therewith for convenient access to operative areas of the patient's mouth.
In the use of dental tools, held within a dental tool holder, it is often found that the jaw separation of the patient is inadequate to allow the tool holder carrying a suitable attachment such as a drill, burr, anchor, reamer and the like to be placed in operative position with respect to the teeth of the patient, especially the posteriors. In the vestibular area of the mouth, it has also been found that the cheek and the tongue do not readily permit access to the normal tool holder provided with conventional tool attachment extensions.
In the aforementioned co-pending application Ser. No. 928,557, there is described a dental tool having a body member provided with an operative end portion for association with the teeth of a patient and a shank extending from the operative end portion for association with a conventional dental handpiece. The shank is provided with a number of sections each of which can preferably be separated from the next adjacent section. Each section includes a circumferential groove for removably engaging the shank in a handpiece. The entire shank is provided with a flat surface along one side of the shank for driving engagement with the handpiece. In order to facilitate the severence of each section from the next adjacent one, a circumferentially tapered notch is disposed between the sections.
The dental tool described is utilized in conjunction with a dental handpiece, of the type described in my U.S. Pat. No. 3,369,298. In such dental handpiece, there is provided an aperture for receiving the shank portion. The upper portion of the aperture includes an inwardly extending flattened side against which the flat surface on the shank of the tool abuts. This flattened surface in the handpiece provides the driving engagement of the shank.
However, the lower edge of the inwardly extending flattened wall in the aperture terminates in an abuttment or ledge. Since the entire length of the shank portion in the aforedescribed co-pending application has a flat surface, only the portion of the shank extending adjacent to the flat wall will be securely retained in the handpiece. However, the portion of the shank beneath the ledge or abuttment will have its flat surface spaced from the aperture in the handpiece. This spacing of the lower part of the shank may cause a vibration or wobble to occur and in some cases could make the dental tool become unlatched from the handpiece.
In the aforementioned co-pending application Ser. No. 887,173, there is described a different type of tool holder, specifically a plastic hand driver which receives the shank portion of a tool. An aperture is formed in the hand driver. At the inward end of the aperture there is again provided an inwardly directed flat wall which terminates in an abuttment. Protrusions extend from an inner portion of the aperture which are snapped into a groove formed circumferentially in the shank to retain the shank in the tool.